Relay



Feb. 2.5, 1941.

C. AH. LARSON RELAY Filed May 22, 1939l 2 Sheets-Sheet .1

WN; WN

Feb. 25, 1941.

C. H. LARSON RELAY Filed May 22, 1959- 2 sheets-sheet' 2 UNITED STATESFATENT' QFFECE c i 2,232,879 v RELAY Crl H. Larson, Euskal-n Ind.,assigner to The Adlakc Company, a corporation of Illinois ApplicationMay 22, 19399 Seal Non1 .27@,008

Y 2 Csims.

This invention relates to mercury switch relays and in order tounderstand the objects of the invention', alt is necessary to definecertain terms that wl be used:

Normal operate time is the time required' te ploduce e. change in theelectrical circuit through the switch when the relay Winding is suddenlyclosed While al1 perte of the switch eze lying in stable equilibrium.

Normal eieese izme is the time required to produce e. change in theelectrical circuit through the switch when the remy windje@ is suddenlyopened while Jl pests of the swcch are wing im stable eemlbum.

Nome operaie i'ecglcifcg is the mmnmm peioc emilie@ which the eleywinding muet be pelmtted "se open im @met that the mec mel operate eebeieeole when me winding is suddezny dosed. Usuem ieugh mi; 2@ awegzs,me 'ecs cpe'ate mcg/"cling cime is the l equyed fol' he switch y WindHmmm femeeemtimg sie switch (i. e. um es eet) bhe ms the che ele csczeu'i through relay The mmmum ve-mes ere te proeven@ immediate changein eil-culi: condzcn im the event of samuel-mel recycling' conditicns,eed the maximum leises eye Usually given to hold. the operezicm of xeleyicc reasonable cycles er to meet; some other specizs ooemtiefcondtion.,

(Ci. 2mn-97) With the above definitions in mind, it is broad- 1y theobject of this invention to povde e mer- @my switch relay that can fulcertain l'eley specicatcns that have heretofore been mp0ssible to meet,et leest with. releys of this type. To accomplish, this end, two @medelay elements are used m such e we; that them action coe-1- relesed andthe action of one modifies o1' efects im seme wey the action of meother.

I More specicey, it is se oojeo cf 'this :leventime. ce jecvie "eayswhich efe cheecterized neme sie 'io meet cerfee eminem opeseu'le emolyeeese yequiemees, and else embody quick femmes either ccmnectiom withoper1 se m time.,

othel am@ edvent elefs {Esegue-ed, as

ces'

mum oemwe time; en@ Figs, l@ ci ci." circuits which. flmetommg' of :the

mmmesic lmsmtes used am explaining the heck cemteci', switch shewe in "Er v v Certain preferred forms of the invention have been illustrated inthe drawings and will be hereinaiter described in compliance withSection 4888 of the Revised Statutes, but the invention is not limitedto the speciiic disclosure contained herein, and the appended claimsshould be construed as broadly as the prior art will permit.

Front contact relay (Figs. 1-5} Before describing in detail the frontcontact relay shown in Figs. l-5 inclusive, it will be helpful toexplain briefly an electrical circuit that requires the use of a relayoi.' the type in question. The electrical circuit, of course, is merelyillustrative of many such circuits that require relays of unusualoperating characteristics of the kind which the present relay possesses.

Referring, then, to Fig. 6, a load is shown at 20 which is controlled bythe combined action of a relay 2| having certain time delaycharacteristics and a relay 22 of the fast acting type. The relay 2| isa front contact relay having its coil connected across lead wires 23 and24, but in series with the contacts generally designated 25. of therelay 22. The contacts, generally designated 26, of the relay 2| areconnected across the leads 23 and 24, but in series with the operatingcoil of the relay 22, and the load 2U is connected across this lattercoil.

Upon energizing the leads 23 and 24, the relay 2| closes the contacts 26after a predetermined time interval (normal operate time) which in' turnenergizes the relay 22 and operates the load 20. The relay 22, however,is a quick make, quick break, relay which immediately upon energization,opens the contacts 25. This results in de-energization of the operatingcoil for the relay 2|. Hence the contacts 26 are again opened, but thisreopening of the contacts 26 must not take place until a certain minimumtime has elapsed to energize the load 2U. 'Ihis minimum time determinesthe specied minimum release time for the relay 2|. l

Stated in other words, any energization of the leads 23 and 24, ifsustained a sufficient length of time causes the load 20 to be operatedfor a given interval of time (minimum release time for the relay 2|),but only after a given time interval has elapsed subsequent to theenergization of the leads 23 and 24 (normal operate time for the relay2|). Hence the relay 2| in so far as its function has thus far ybeendescribed, must have a predetermined normal operate time and apredetermined minimum release time. In addition to thesecharacteristics, the relay must also have quick operate resetcharacteristics so that if the leads 23 and 24 are first energized andthen de-energized before the contacts 26 have had an opportunity toclose, the prescribed normal operate time will elapse between the secondenergization of the leads 23 and 24 and the closing of the contacts 26.summarized, the relay 2| must have the following operatingcharacteristics: It must be a front contact relay with predeterminednormal operate time, predetermined minimum release time, and have quickoperate reset, so that normal operate time will be obtained even undersubnormaloperate recycling conditions.

The relay shown in Figs. 1-5 inclusive has these characteristics.

It comprises a coil 21 provided with poles 28 and 29 within which therelay switch generally designated 30 is suitably mounted.

The switch 30 comprises a switch envelope 3| of low expansion,boro-silicate glass throui'h the base of which lead-ins 32 and 33,preferably oi molybdenum or tungsten, are pinch-sealed. The lead-insproject upwardly into the switch envelope and are covered for portionsof their lengths by insulating sleeves 34 and 35, respectively, leavingexposed electrodes 36 and 31 which are adapted to be bridged andunbridged by ap propriete manipulation of the mercury ll 3B within theenvelope.

A glass thimble, generally designated 39, is telescoped over theelectrode 31 and is iused to the sleeves 34 and 35, as indicated at 40.The thimble is provided with a relatively large opening 4| at one sideto permit mercury to pass freely to and from the thimble except only asthe movement of the mercury is retarded by the action of a time delayelement 42 which consists of a gas pervious plug of ceramic material,

preferably Alundum, Grade RA 98 (manufactured by the Norton Company ofWorcester, Massachusetts), bonded by fusion, or other suitable means,into an opening provided in the upper end of the thirrible. The plugoffers a predetermined impedance to the flow of gas to and from thethlmble Whenever the mercury in the envelope complete covers the opening4| and the plug is, ot course, impervious to mercury.

The electrode 31 extends above the insulating sleeve 35 and issurrounded by a ceramic cup 43 which is bonded to the upper end of theinsulating sleeve 35 and forms a reservoir for a small pool of mercury44 which .is always in contact with the electrode 31 andl permits thebridging of the electrodes 36 and 31 to be accomplished by a mercury tomercury contact.

The mercury fill 33 within theI displacer is manipulated by amagnetically controlled plunger or displacer, generally designated 45,which comprises an inner glass thimble 4B closed at its upper end by aporous wall 41 which constitutes a second time delay element within theswitch. The thimble 46 has an iron sleeve 48 telescoped over it, andconstituting the armature of the relay. The armature is split on oneside as indicated at 49, so that the relay may be used eiiiciently withalternating current, and the armature is held in place upon the thimble46 by upper and lower cushioning springs 50 and 5|, respectively, whichclamp guide washers 52 and 53 in place against the ends of the ironsleeve. The springs 50 and'5l frictionally engage the projecting ends ofthe thimble 46 and effectively hold the component parts of the displacerin assembled relation. The guide washers 52 and 53 have prongs 54 whichguide the displacer in its movement within the envelope. and theperipheral cuts 55 between the prongs permit mercury to pass freely bythe washers between the displacer and the switch envelope.

The switch envelope before being sealed off at 56, is filled with asuitable inert gas, such as helium, hydrogen, or the like, or a mixtureof such gases.

The operation of the switch is illustrated in Figs. 1-4 inclusive, andparticular attention should be paid to the function which the sideopening 51 in the thimble 46 has in giving the relay its desiredoperating characteristics.

Assuming that the switch parts are in stable equilibrium with the coilde-energized (as shown in Fig. 1) the rst thing that happens uponenergization of the coil is the lowering of the displacer to theposition in which it is shown in Fig. 2, Since the opening 5| in thedisplacer I' thimble 46 is submerged in the mercury ll .dur-

ing the downwardv movement of the displacer, gas is trapped within theupper portion of the displacer, and the result is that the mercury levelwithin the displacer is forced down to a position indicated at 58, andthe outside mer- -cury level rises to the positon'indicated at 59.

Assuming now that the coil 21 remains energized, the mercury within thedisplacer thimble tends to rise due to the equalization of the gaspressures within and outside of the displacer thimble, and the time thatis required for the l L inside mercury level to reach the top margin 60of the opening 4i is determined solely by the impedance which the timedelay element 41 in the displacer thimlole 4S oifers to the passage ofgas escaping from the thimble. Thereafter, the movement of mercuryupwardly within the fixed thimble 39 to close the contacts through theswitch, is determined by the joint action of the time delay element 41in the displac'er thimble 46 andthe time delay element 42 in the xedthimble 3Q. These two time delay elements are chosen with porositieseffecting a total elapse of time, such that the time required for themercury. to rise from the level indicated at 58 up to and into contactwith the mercury pool 44 is equal to the specied normal operate time ofthe relay. 1f

`the relay coil continues to be energized, stable equilibrium is finallyreached when the mercury level throughout the switch is equalized at thelevel indicated by the line 6|.

However, when the relay is recycled through its own contacts, as in Fig..6, the mercury level within the thimble 3S rises only to a heightsufficient to close the contacts, at which instant the relayv coil is(ie-energized through contacts 25 of the relay 22. The ilrst thing thathappens under these circumstances is that the displacer d rises becauseof its buoyancy to the position shown in Fig. 3, where it is momentarilyretarded'in its upward movement by reason of the 'fact that the totaleffective weight of-the displacer includes the mercury column that iscarried up within the displacer during its upward movement. It should benoted that this position of the displacer is lower than the normaldeenergized position of the displacer and also that the outside mercurylevel indicated at 52 is above the opening 51 in the displacer thimble46. As gas slowly enters the displacer through the porous wall 41, themercury within the thimble 46 gradually recedes, lessening the e'iectiveweight on the displacer and causing it to slowly rise until the opening51 reaches the outside mercury level 62, as indicated in Fig. 4. Duringthis time, the circuit between the electrodesl 36 and 31 remains closed.At the instant that the switch parts reach the position shown in Fig. 4,gas is permitted to enter the interior of the displacer through the sideopening 51 which' in eiect bypasses the time delay element 41 and Yimmediately causes the mercury within the displacer to fall. to thelevel in which it is shown in Fig. 1 and simultaneously therewith, thedisplacer rises to its full height, as shown in Fig. 1.

The time required for the displacer to move to the position shown inFig. 3 and then with retarded motion reach the position shown in Fig. 4and nally move swiftly to the position shown in Fig. l, determines theminimum time that the circuit through the electrodes '3G and 31 whenonce closed is permitted to remain closed, or in other words, thisfunction of the relay determines the minimum release time of the relay.For the circuit shown in Fig. 6, the minimum release time is only .6 ofa second, which for all practical purposes, is substantially no timedelay at all. y

In my prior Patent 1,967,947, a displacer is shown which has somewhatthe same characteristie action as the one disclosed in the presentapplication, but the relay there shown does not have the peculiaroperating characteristics that are obtained by the use of two time delayelements working together. For example, it is impossible with the relayshown in Patent No. 1,967,- 947 to have a minimum operate or releasetime because subnormal recycyling conditions can under certaincircumstances bring about a substantially instantaneous closing of thecircuit -upon a change in the condition of the relay coil.

lcall for a minimum time delay ci sixty seconds when making the circuit,if after thirty seconds of that time has elapsed, the relay coil isVcie-energized, the plunger will immediately rise and carry with it acolumn of mercury that will at once bridge the contacts. The relay of myprior patent, therefore, is incapable of insuring that the contacts willnot close before the elapse of a specined minimum operate or releasetime. ."Eiy way of contrast, if the mercury level in the presentinvention has almost reached the mercury pool 44 associated with theelectrode y31 at the instant that the coil 21 becomes rie-energized, thesubstantially instantaneous rise of the displacer t5 and concurrentyfalling away of the mercury level to the position in which it is shownin Fig. 1 insures that the relay will not make a false contact.

There is a possibility that when the specified minimum release .time isrelatively high, a particular positioning of the switchparts at theinstant that the relay is cle-energized, would result in a false makingof the circuit through the switch. To that extent, the particular relaydisclosed has a limitation, but if on the other hand, the operatingcharacteristics do not require a minimum release time, as is many timesthe case, the opening 51 maybe placed at a sutillthat there is aninstantaneous, or at least substantially instantaneous drop away ofmercury from the contacts upon de`energization of the coil 21, theswitch has what is termed quick operate reset inasmuch as everyenergization of the coil will always produce the required normal operatetime irrespective of the time during which the coii was previouslyde-energized.

By way of specific example, if the relay 2i of Fig. 5 requires anormally open contact with a normal operate time of 3.5 seconds, and amim'- mum release time of .6 second with a quick operate reset feature,the time delay element 41 in the plunger may have a .4 second time delay(time required to produce stable equilibrium in the switch after thecoil has been energized, assuming that the iixed thimble 39 wereomitted) and the time delay in the fixed thimble 39 may have a timedelay of 3.1 seconds.

It a longer minimum release time were required, the opening 51 might beprovided with a ceramic plug similar to the plug 41, or if a shorterminimum release time were required, the hole 51 could be raisedproportionately to within this result. Obviously, these values arenecessarily determined empirically in actual practice.

Back Contact relay l In Figs. 9 and 10, diagrammatic illustrativecircuits are shown requiring back contact relays having somewhat unusualoperating characteristics.

In Fig. 9, by way of example, the relay 1D may, because of the apparatuswhich it controls, be required to have its contacts 1l close with anormal release time of 3.5 seconds and open with a normal operate timeof .6 second, regardless of the operating characteristics of the controlcontact 12. Or the relay 10 may be used in a self re-cycling circuitsuch as shown in Fig. l0, in which case the relay must have a quickrelease reset. The relay shown in Figs. 7 and 8 is satisfactory for usewith either of these circuits assuming that the time delay elements areproperly chosen for values and the side opening in the dispiacer issuitably positioned.

The construction of the relay is identical with the relay shown in Figs.1-4 inclusive with the exception that the parts are differentlyproportioned, and the displacer relief vent 51 is located in a bulge 13provided in the lower portion of the displacer thimble. inasmuch as theparts of this relay are functionally the same as those 0in the relayshown in Figs. l-A inclusive, like from the displacr 45 allows thedispiacer to rise further thereby lowering the level of the mercury lito a point below the mercury opening in the thimble. The mercury columnwithin the thimble is thus undermined and falls immediately, breakingthe circuit through the electrodes. The short interval required for themercury column to be undermined by the gas entering the displacerthrough the vent 51 enables the minimum operate time of .6 second to bemet.

If a longer minimum operate time is required, the vent 51 may beequipped with a porous plug to delay the admittance of gas to theinterior of the displacer. If a shorter minimum time delay is desired,the vent. 51 may be located at a higher level.

Again, the situation exists that if the relay has a substantial minimumoperate time requirement, the ability o! the switch to have a quickrelease reset is limited. On the other hand, when the minimum operatetime is relatively small, the

quick release reset is capable of being achieved.

The combination of a time delay in a plunger with a time delay ilxed tothe electrode, makes it possible to obtain time delays on both theopening and closing of the contact, which otherwise would be impossibleto produce. It is, of course, possible to produce a delay on bothopening and closing of. a contact with a time delay on either theelectrode or the plunger alone, but not with quick reset features. Anadditional advantage is that when the time delays on both make andbrealt have to be held to 'very close limits, the time delays may beindividually adjusted without one time delay adjustment in terferingwith the other, v

In both front and back contact forms of the invention, the limitation inthe quick reset characteristics of tire switches may be avoided and areavoided by none circuits in which the re- Clfilig of the relay iscontrolled by the switch t contacts. For eitample, by using the circuitshown in Fig. 6 for the :iront contact switch oi;

Figs.

Zi-5 inclusive, the switch functions with quick operate reset, and whenthe circuit shown i of Figs. 7 and 8, the switch functions with quickrelease reset.

I claim:

1. In a mercury switch relay having prescribed operatingcharacteristics, the combination of a relay coil, a switch associatedwith the coil, said switch comprising a switch envelope, spaced electrodes in the envelope, a mercury fill, a hollow displacer responsive tothe coil for shifting the mercury level, and cooperating time delayelements associated with one of said electrodes to delay the movement ofmercury with relation to said electrode upon a change in the conditionof the electrical circuit through the coil, one oi said time delayelements comprising a gas lealiu age device associated with thedisplacer, and the other comprising a relatively xed gas leakage deviceassociated with said one electrode, and means including at least one ofsaid time delay elements for maintaining the column oi mercury abovesaid one electrode for a predetermined time to insure that, once theelectrodes 'have been bridged with mercury, they will rcmain bridged forat least a brief period of time. 2. In a mercury switch relay havingprescribed operating characteristics, the combination of a relay coil, aswitch associated with the coil, said switch comprising a switchenvelope, spaced elec* trodes in the envelope, a mercury ll, a hollowdisplacer responsive to the coil for shifting the mercury level, andcooperating time delay elements associated with one of said electrodesto delay the movement oi? mercury with relation to said electrode upon achange in the condition of the electrical circuit through the coil, oneof said time delay elements comprising a gas leakage device associatedwith the displacer and the other comprising a relatively fixed gasleakage device associated with said one elec trode, and means includingat least one of said time delay elements for insuring that 'the switchshall possess minimum operate time characteristicS.

CARL H. LARS-ON.

